US6242801B1 - Semiconductor device - Google Patents

Semiconductor device Download PDF

Info

Publication number
US6242801B1
US6242801B1 US08/750,974 US75097497A US6242801B1 US 6242801 B1 US6242801 B1 US 6242801B1 US 75097497 A US75097497 A US 75097497A US 6242801 B1 US6242801 B1 US 6242801B1
Authority
US
United States
Prior art keywords
island
wires
section
semiconductor device
cut
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
US08/750,974
Inventor
Masashi Sano
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Rohm Co Ltd
Original Assignee
Rohm Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Rohm Co Ltd filed Critical Rohm Co Ltd
Assigned to ROHM CO., LTD. reassignment ROHM CO., LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: SANO, MASASHI
Application granted granted Critical
Publication of US6242801B1 publication Critical patent/US6242801B1/en
Assigned to ROHM CO., LTD. reassignment ROHM CO., LTD. CORRECTIVE ASSIGNMENT TO CORRECT THE ASSIGNEE'S ADDRESS, PREVIOUSLY RECORDED AT REEL 011710 FRAME 0485. Assignors: SANO, MASASHI
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Images

Classifications

    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L24/00Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
    • H01L24/01Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L24/42Wire connectors; Manufacturing methods related thereto
    • H01L24/47Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L24/49Structure, shape, material or disposition of the wire connectors after the connecting process of a plurality of wire connectors
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00Details of semiconductor or other solid state devices
    • H01L23/48Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00Details of semiconductor or other solid state devices
    • H01L23/48Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor
    • H01L23/488Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor consisting of soldered or bonded constructions
    • H01L23/495Lead-frames or other flat leads
    • H01L23/49503Lead-frames or other flat leads characterised by the die pad
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00Details of semiconductor or other solid state devices
    • H01L23/48Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor
    • H01L23/488Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor consisting of soldered or bonded constructions
    • H01L23/495Lead-frames or other flat leads
    • H01L23/49541Geometry of the lead-frame
    • H01L23/49562Geometry of the lead-frame for devices being provided for in H01L29/00
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/26Layer connectors, e.g. plate connectors, solder or adhesive layers; Manufacturing methods related thereto
    • H01L2224/31Structure, shape, material or disposition of the layer connectors after the connecting process
    • H01L2224/32Structure, shape, material or disposition of the layer connectors after the connecting process of an individual layer connector
    • H01L2224/321Disposition
    • H01L2224/32151Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
    • H01L2224/32221Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
    • H01L2224/32245Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42Wire connectors; Manufacturing methods related thereto
    • H01L2224/44Structure, shape, material or disposition of the wire connectors prior to the connecting process
    • H01L2224/45Structure, shape, material or disposition of the wire connectors prior to the connecting process of an individual wire connector
    • H01L2224/45001Core members of the connector
    • H01L2224/45099Material
    • H01L2224/451Material with a principal constituent of the material being a metal or a metalloid, e.g. boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te) and polonium (Po), and alloys thereof
    • H01L2224/45138Material with a principal constituent of the material being a metal or a metalloid, e.g. boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te) and polonium (Po), and alloys thereof the principal constituent melting at a temperature of greater than or equal to 950°C and less than 1550°C
    • H01L2224/45144Gold (Au) as principal constituent
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42Wire connectors; Manufacturing methods related thereto
    • H01L2224/47Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/4805Shape
    • H01L2224/4809Loop shape
    • H01L2224/48091Arched
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42Wire connectors; Manufacturing methods related thereto
    • H01L2224/47Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/481Disposition
    • H01L2224/48151Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
    • H01L2224/48221Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
    • H01L2224/48245Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic
    • H01L2224/48247Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic connecting the wire to a bond pad of the item
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42Wire connectors; Manufacturing methods related thereto
    • H01L2224/47Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/481Disposition
    • H01L2224/48151Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
    • H01L2224/48221Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
    • H01L2224/48245Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic
    • H01L2224/48257Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic connecting the wire to a die pad of the item
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42Wire connectors; Manufacturing methods related thereto
    • H01L2224/47Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/484Connecting portions
    • H01L2224/48463Connecting portions the connecting portion on the bonding area of the semiconductor or solid-state body being a ball bond
    • H01L2224/48465Connecting portions the connecting portion on the bonding area of the semiconductor or solid-state body being a ball bond the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42Wire connectors; Manufacturing methods related thereto
    • H01L2224/47Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/49Structure, shape, material or disposition of the wire connectors after the connecting process of a plurality of wire connectors
    • H01L2224/491Disposition
    • H01L2224/4911Disposition the connectors being bonded to at least one common bonding area, e.g. daisy chain
    • H01L2224/49111Disposition the connectors being bonded to at least one common bonding area, e.g. daisy chain the connectors connecting two common bonding areas, e.g. Litz or braid wires
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/73Means for bonding being of different types provided for in two or more of groups H01L2224/10, H01L2224/18, H01L2224/26, H01L2224/34, H01L2224/42, H01L2224/50, H01L2224/63, H01L2224/71
    • H01L2224/732Location after the connecting process
    • H01L2224/73251Location after the connecting process on different surfaces
    • H01L2224/73265Layer and wire connectors
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L24/00Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
    • H01L24/01Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L24/42Wire connectors; Manufacturing methods related thereto
    • H01L24/44Structure, shape, material or disposition of the wire connectors prior to the connecting process
    • H01L24/45Structure, shape, material or disposition of the wire connectors prior to the connecting process of an individual wire connector
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L24/00Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
    • H01L24/01Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L24/42Wire connectors; Manufacturing methods related thereto
    • H01L24/47Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L24/48Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/01Chemical elements
    • H01L2924/01005Boron [B]
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/01Chemical elements
    • H01L2924/01006Carbon [C]
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/01Chemical elements
    • H01L2924/01013Aluminum [Al]
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/01Chemical elements
    • H01L2924/01079Gold [Au]
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/10Details of semiconductor or other solid state devices to be connected
    • H01L2924/11Device type
    • H01L2924/12Passive devices, e.g. 2 terminal devices
    • H01L2924/1204Optical Diode
    • H01L2924/12043Photo diode
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/15Details of package parts other than the semiconductor or other solid state devices to be connected
    • H01L2924/181Encapsulation

Definitions

  • the present invention relates to a semiconductor device in which a semiconductor element is mounted on an island, and especially to a semiconductor device in which an island has a characteristic shape.
  • a semiconductor device has a structure as described below.
  • a photodetector device having a semiconductor element such as a photodiode is taken as an example.
  • the photodetector device is composed of a common lead 31 having at one end an approximately square-shaped island 31 a , specific leads 32 and 33 formed on both sides of and approximately parallel with the common lead 31 , a semiconductor element 34 die-bonded on the island 31 a , a plurality of wires 35 made of gold or other for electrically connecting the semiconductor element 34 to the top surface of the island 31 a and to the specific leads 32 and 33 by wire bonding, and an approximately square-shaped resin seal 36 made of epoxy resin for sealing in the semiconductor element 34 and the wires 35 (the resin seal 36 actually is opaque, though it is shown as transparent in FIG. 4 ).
  • a plurality of projection-like electrode pads made of aluminum or other.
  • bonded wires 35 of which four are, at the other end, bonded on the top surface of the island 31 a and two are, at the other end, bonded on the specific leads 32 and 33 , respectively.
  • the first four wires are electrically connected to the island 31 a so as to be grounded, and thus serve to adjust the resistance against a current flowing between the specific leads 32 and 33 .
  • the resin seal 36 is so formed as to seal in the semiconductor element 34 and the wires 35 as shown in FIG. 5 by use of a resin-forming mold (not shown).
  • the resin seal 36 has, at its portion approximately above the semiconductor device 34 , a hemispherical condenser lens 37 for leading light from outside to the semiconductor element 34 .
  • this photodetector has been suffering from a following problem.
  • the above resin seal 36 is heated to seal in the semiconductor element 34 and the wires 35 , and thereafter, as the resin seal 36 cools down, it develops contraction stress inside itself. This causes the wires 35 to be pulled together with the resin, of which the resin seal 36 is made, in the direction of the inward contraction of the resin. On the other hand, the island 31 a , on which one end of each wire 35 is stitch-bonded, contracts far less than the resin seal 36 because of their different thermal expansion coefficients.
  • the wires 35 are subjected to force that pulls them in the direction of the contraction of the resin and that tends to tear the ends of the wires 35 off the island 31 a , and eventually the wires 35 are broken as shown in FIG. 6 . Moreover, the same can be caused even by variations in ambient temperature.
  • An object of the present invention is to provide a highly reliable semiconductor device that is substantially free from wire breakage.
  • a semiconductor device comprising a lead terminal having an island at one end, a semiconductor element whose bottom surface is connected to the island, one or more wires that connect the top surface of the semiconductor element to the island, and a resin seal that seals in the semiconductor element and the wires
  • said island has a cut formed between a section on which said semiconductor element is mounted and a section on which said wires are bonded.
  • the cut is so formed as to extend below all the wires.
  • FIG. 1 is a partly-removed plan view showing a photodetector as an example of the semiconductor device of the present invention
  • FIGS. 2A, 2 B, 2 C, 2 D and 2 E are partly-removed plan views each showing a modified example of the semiconductor device of the present invention
  • FIG. 3 is a partly-removed plan view showing another modified example of the semiconductor device of the present invention.
  • FIG. 4 is a partly-removed plan view showing a conventional semiconductor device
  • FIG. 5 is a perspective view of the principal portion of the conventional semiconductor device.
  • FIG. 6 is a diagram explaining a state of wire breakage in the conventional semiconductor device.
  • FIGS. 1 and 2A, 2 B, 2 C, 2 D and 2 E a photodetector device having a semiconductor element including a photodiode element
  • a photodiode element a photodetector device having a semiconductor element including a photodiode element
  • the semiconductor device comprises a common lead 1 (lead terminal) having at one end an approximately square-shaped island 1 a , specific leads 2 a and 2 b formed on both sides of and approximately parallel with the common lead 1 , a photodiode element 3 that is die-bonded on the island 1 a , a plurality of wires 4 made of gold or other for electrically connecting the photodiode element 3 to the top surface of the island 1 a and to the specific leads 2 a and 2 b by wire bonding, and an approximately square-shaped resin seal 5 made of epoxy resin for sealing in the photodiode element 3 and the wires 4 (the resin seal 5 actually is opaque, though it is shown as transparent in FIG. 1 ).
  • a cut 1 b is formed between the section on which the photodiode element 3 is mounted and the section on which the wires 4 are bonded.
  • This cut 1 b is formed along one side (the side where stitch-bonding of the wires 4 is present in the figure) of the photodiode element 3 .
  • the length A of the cut 1 b is about 1.9 mm, and the width B of the island is about 2.3 mm. Therefore, the length A of the cut 1 b is approximately 80% of the width B of the island.
  • the width C of the cut 1 b is about 0.4 mm.
  • the wires 4 are individually bonded at one end. Of these wires 4 , four are, at the other end, stitch-bonded on the top surface of the island 1 a , with the wires crossing over the cut 1 b , and two are, at the other end, stitch-bonded on the specific leads 2 a and 2 b , respectively.
  • the resin seal 5 is formed by molding epoxy resin, which is a thermosetting resin, into a shape as described earlier and as shown in FIG. 5 by use of a conventional resin-forming mold.
  • the resin seal 5 is formed, for example, by applying heat-molten epoxy resin over the photodiode element 3 and the wires 4 to seal them in, and then letting the resin cool down to room temperature.
  • the island 1 a having a cut 1 b formed between the section on which the photodiode element 3 is mounted and the section on which the wires 4 are bonded as described earlier, easily deforms in the direction (shown by arrows in FIG. 1) in which those two sections come closer to or apart from each other about the cut 1 b . Accordingly, the island 1 a allows its portion around the cut 1 b to deform easily with the inward contraction of the epoxy resin.
  • the cut 1 b is so formed as to extend below all the wires 4 so that the island 1 a is in a form to deform readily in the direction in which its two sections come close to or apart from each other about the cut 1 b . Accordingly, the island 1 a allows its portion around the cut 1 b (including the portion on which the wires 4 are bonded) to deform easily with the contraction of the resin. As a result, the possibility of wire breakage is reduced significantly.
  • the cut 1 b is formed, as shown in FIG. 1, along one side of the square-shaped photodiode element 3 so as to be parallel with that side.
  • FIG. 2A shows a cut pattern that is substantially the same as that shown in FIGS. 1, and 2 B, 2 C, 2 D and 2 E show other cut patterns with which the object of the present invention is achieved.
  • the cut 1 b can be formed in any shape and in any position as long as the wires 4 cross over it.
  • the present invention can be invariably applied to semiconductor devices having one or more wires.
  • the length and width of the cut 1 b are not limited to particular values as shown in the above embodiment, and it is also possible to form more than one cuts 1 b.
  • the cut 1 b is formed with one end open, i.e. like a notch, in the above embodiment, it may be formed without an open end, i.e. as a through hole 6 , as shown in FIG. 3 .
  • the through hole 6 needs to be large enough to allow the island to deform easily with the contraction of the epoxy resin.
  • the diameter of the through hole 6 (or the major length of the hole, if it is elongated) needs to be close to the width of the island.
  • an island has a cut formed between a section on which a semiconductor element is mounted and a section on which wires are bonded.
  • the semiconductor device is formed, for example, by applying heat-molten thermosetting resin over the semiconductor element and the wires so that they are sealed in in a resin seal.
  • the resin as it cools down after curing, develops contraction strain inside itself. This causes the wires as well as the resin to be subjected to force that pulls them inward in the direction of the contraction.
  • the island has, as described above, a cut formed between the section on which the semiconductor element is mounted and the section on which the wires are bonded, so that the island is in a form to deform readily in the direction in which its two sections come close to or away from each other about the cut. Accordingly, the island allows its portion around the cut to deform easily with the inward contraction of the resin.
  • the island 1 a is also pulled in the same direction in which the epoxy resin contracts.
  • the possibility of breakage of the wires at their ends bonded on the island 1 a can be reduced significantly.
  • the present invention can be usefully applied to semiconductor devices including a photodiode element or any other type of semiconductor element, and is especially suitable for semiconductor devices whose semiconductor elements, lead terminals, and wires connecting these are resin-molded.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Light Receiving Elements (AREA)
  • Structures Or Materials For Encapsulating Or Coating Semiconductor Devices Or Solid State Devices (AREA)
  • Lead Frames For Integrated Circuits (AREA)

Abstract

A semiconductor device includes a lead terminal that has an island at one end, a semiconductor element whose bottom surface is connected to the island, one or more wires that connect a top surface of the semiconductor element to the island, and a resin seal that seals in the semiconductor device and the wires. In the island, a cut is formed between a section on which one semiconductor element is mounted and a section on which the wires are bonded.

Description

TECHNICAL FIELD
The present invention relates to a semiconductor device in which a semiconductor element is mounted on an island, and especially to a semiconductor device in which an island has a characteristic shape.
BACKGROUND ART
Conventionally, a semiconductor device has a structure as described below. Here, a photodetector device having a semiconductor element such as a photodiode is taken as an example.
As shown in FIG. 4, the photodetector device is composed of a common lead 31 having at one end an approximately square-shaped island 31 a, specific leads 32 and 33 formed on both sides of and approximately parallel with the common lead 31, a semiconductor element 34 die-bonded on the island 31 a, a plurality of wires 35 made of gold or other for electrically connecting the semiconductor element 34 to the top surface of the island 31 a and to the specific leads 32 and 33 by wire bonding, and an approximately square-shaped resin seal 36 made of epoxy resin for sealing in the semiconductor element 34 and the wires 35 (the resin seal 36 actually is opaque, though it is shown as transparent in FIG. 4). On the top surface of the above semiconductor element 34 are formed a plurality of projection-like electrode pads (not shown) made of aluminum or other. On these electrode pads are bonded wires 35, of which four are, at the other end, bonded on the top surface of the island 31 a and two are, at the other end, bonded on the specific leads 32 and 33, respectively. The first four wires are electrically connected to the island 31 a so as to be grounded, and thus serve to adjust the resistance against a current flowing between the specific leads 32 and 33.
The resin seal 36 is so formed as to seal in the semiconductor element 34 and the wires 35 as shown in FIG. 5 by use of a resin-forming mold (not shown). The resin seal 36 has, at its portion approximately above the semiconductor device 34, a hemispherical condenser lens 37 for leading light from outside to the semiconductor element 34.
However, this photodetector has been suffering from a following problem.
The above resin seal 36 is heated to seal in the semiconductor element 34 and the wires 35, and thereafter, as the resin seal 36 cools down, it develops contraction stress inside itself. This causes the wires 35 to be pulled together with the resin, of which the resin seal 36 is made, in the direction of the inward contraction of the resin. On the other hand, the island 31 a, on which one end of each wire 35 is stitch-bonded, contracts far less than the resin seal 36 because of their different thermal expansion coefficients.
As a result, the wires 35 are subjected to force that pulls them in the direction of the contraction of the resin and that tends to tear the ends of the wires 35 off the island 31 a, and eventually the wires 35 are broken as shown in FIG. 6. Moreover, the same can be caused even by variations in ambient temperature.
An object of the present invention is to provide a highly reliable semiconductor device that is substantially free from wire breakage.
DISCLOSURE OF THE INVENTION
According to the present invention, in a semiconductor device comprising a lead terminal having an island at one end, a semiconductor element whose bottom surface is connected to the island, one or more wires that connect the top surface of the semiconductor element to the island, and a resin seal that seals in the semiconductor element and the wires, said island has a cut formed between a section on which said semiconductor element is mounted and a section on which said wires are bonded.
Moreover, according to the present invention, in a semiconductor device as described above, the cut is so formed as to extend below all the wires.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a partly-removed plan view showing a photodetector as an example of the semiconductor device of the present invention;
FIGS. 2A, 2B, 2C, 2D and 2E are partly-removed plan views each showing a modified example of the semiconductor device of the present invention;
FIG. 3 is a partly-removed plan view showing another modified example of the semiconductor device of the present invention;
FIG. 4 is a partly-removed plan view showing a conventional semiconductor device;
FIG. 5 is a perspective view of the principal portion of the conventional semiconductor device; and
FIG. 6 is a diagram explaining a state of wire breakage in the conventional semiconductor device.
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 and 2A, 2B, 2C, 2D and 2E. In the following descriptions, a photodetector device having a semiconductor element including a photodiode element (hereinafter the semiconductor element is referred to as a photodiode element) is dealt with as an example of the semiconductor device of the present invention. This however does not suggest that application of the present invention is limited to particular types of semiconductor device.
As shown in FIG. 1, the semiconductor device comprises a common lead 1 (lead terminal) having at one end an approximately square-shaped island 1 a, specific leads 2 a and 2 b formed on both sides of and approximately parallel with the common lead 1, a photodiode element 3 that is die-bonded on the island 1 a, a plurality of wires 4 made of gold or other for electrically connecting the photodiode element 3 to the top surface of the island 1 a and to the specific leads 2 a and 2 b by wire bonding, and an approximately square-shaped resin seal 5 made of epoxy resin for sealing in the photodiode element 3 and the wires 4 (the resin seal 5 actually is opaque, though it is shown as transparent in FIG. 1).
In the island 1 a, a cut 1 b is formed between the section on which the photodiode element 3 is mounted and the section on which the wires 4 are bonded. This cut 1 b is formed along one side (the side where stitch-bonding of the wires 4 is present in the figure) of the photodiode element 3. The length A of the cut 1 b is about 1.9 mm, and the width B of the island is about 2.3 mm. Therefore, the length A of the cut 1 b is approximately 80% of the width B of the island. The width C of the cut 1 b is about 0.4 mm. Moreover, on the top surface of the photodiode element 3, six electrode pads (not shown) made of aluminum are formed, and, on these electrode pads, the wires 4 are individually bonded at one end. Of these wires 4, four are, at the other end, stitch-bonded on the top surface of the island 1 a, with the wires crossing over the cut 1 b, and two are, at the other end, stitch-bonded on the specific leads 2 a and 2 b, respectively.
In the photodetector device having the above structure, the resin seal 5 is formed by molding epoxy resin, which is a thermosetting resin, into a shape as described earlier and as shown in FIG. 5 by use of a conventional resin-forming mold.
Specifically, the resin seal 5 is formed, for example, by applying heat-molten epoxy resin over the photodiode element 3 and the wires 4 to seal them in, and then letting the resin cool down to room temperature.
However, as the epoxy resin cools down after heat curing, it develops contraction stress inside itself. This causes the wires 4 as well as the epoxy resin to be subjected to force that pulls them inward in the direction of the contraction. On the other hand, the island 1 a, having a cut 1 b formed between the section on which the photodiode element 3 is mounted and the section on which the wires 4 are bonded as described earlier, easily deforms in the direction (shown by arrows in FIG. 1) in which those two sections come closer to or apart from each other about the cut 1 b. Accordingly, the island 1 a allows its portion around the cut 1 b to deform easily with the inward contraction of the epoxy resin.
As a result, when the wires 4 are pulled, at their ends bonded on the island 1 a, in the direction in which the epoxy resin contracts, the island 1 a is also pulled in the same direction in which the epoxy resin contracts. Thus, the possibility of breakage of the wires at their ends bonded on the island 1 a can be reduced significantly.
In this embodiment, the cut 1 b is so formed as to extend below all the wires 4 so that the island 1 a is in a form to deform readily in the direction in which its two sections come close to or apart from each other about the cut 1 b. Accordingly, the island 1 a allows its portion around the cut 1 b (including the portion on which the wires 4 are bonded) to deform easily with the contraction of the resin. As a result, the possibility of wire breakage is reduced significantly.
In the above embodiment, the cut 1 b is formed, as shown in FIG. 1, along one side of the square-shaped photodiode element 3 so as to be parallel with that side. However, this does not suggest any limitation to the way the cut 1 b is formed. In FIG. 2A shows a cut pattern that is substantially the same as that shown in FIGS. 1, and 2B, 2C, 2D and 2E show other cut patterns with which the object of the present invention is achieved. In short, the cut 1 b can be formed in any shape and in any position as long as the wires 4 cross over it. Moreover, although there are four wires 4 crossing over the cut 1 b in the above embodiment, the present invention can be invariably applied to semiconductor devices having one or more wires.
Furthermore, the length and width of the cut 1 b are not limited to particular values as shown in the above embodiment, and it is also possible to form more than one cuts 1 b.
Moreover, although the cut 1 b is formed with one end open, i.e. like a notch, in the above embodiment, it may be formed without an open end, i.e. as a through hole 6, as shown in FIG. 3. In this case, however, in order to achieve the object of the present invention, the through hole 6 needs to be large enough to allow the island to deform easily with the contraction of the epoxy resin. Specifically, the diameter of the through hole 6 (or the major length of the hole, if it is elongated) needs to be close to the width of the island. Of course, it is also possible to form more than one such through hole 6.
Furthermore, although a photodetector device is taken as an example of a semiconductor device in the above embodiment, this does not suggest that application of the present invention is limited to particular types of semiconductor device.
In a semiconductor device according to the present invention, an island has a cut formed between a section on which a semiconductor element is mounted and a section on which wires are bonded. This offers the following advantages.
The semiconductor device is formed, for example, by applying heat-molten thermosetting resin over the semiconductor element and the wires so that they are sealed in in a resin seal. The resin, as it cools down after curing, develops contraction strain inside itself. This causes the wires as well as the resin to be subjected to force that pulls them inward in the direction of the contraction. On the other hand, the island has, as described above, a cut formed between the section on which the semiconductor element is mounted and the section on which the wires are bonded, so that the island is in a form to deform readily in the direction in which its two sections come close to or away from each other about the cut. Accordingly, the island allows its portion around the cut to deform easily with the inward contraction of the resin.
As a result, when the wires are pulled, at their ends bonded on the island, in the direction in which the epoxy resin contracts, the island 1 a is also pulled in the same direction in which the epoxy resin contracts. Thus, the possibility of breakage of the wires at their ends bonded on the island 1 a can be reduced significantly.
Industrial Applicability
As described above, the present invention can be usefully applied to semiconductor devices including a photodiode element or any other type of semiconductor element, and is especially suitable for semiconductor devices whose semiconductor elements, lead terminals, and wires connecting these are resin-molded.

Claims (11)

What is claimed is:
1. A semiconductor device comprising:
an island at only one end of only lead terminal, said island having a first section and second section,
a semiconductor element whose button surface is mounted on said first section of the island,
one or more wires that connect a top surface of the semiconductor element to said second section of the island, and
a resin that seals in the semiconductor device and the wires,
wherein said island has a cut formed between a) said first section of said island on which semiconductor element is mounted b) said second section of said island on which all said wires are bonded.
2. A semiconductor device as claimed in claim 1,
wherein said cut is so formed as to extend below all of said wires.
3. A semiconductor device as claimed in claim 1,
wherein said resin is epoxy resin.
4. A semiconductor device as claimed in claim 1,
wherein said semiconductor element is square-shaped and said cut is formed along one side of the semiconductor element, and wherein said wires that are at one connected to said semiconductor element are stitch-bonded on a top surface of said island such that the wires cross over the cut.
5. A semiconductor device as claimed in claim 4,
wherein said cut is formed to have a length equal to approximately 80% of a width of said island.
6. A semiconductor device comprising:
an island at only one end of only one lead terminal, said island having a first section and second section,
a semiconductor element whose bottom surface is mounted on said first section of the island,
one or more wires that connect a top surface of the semiconductor element to said second section of the island, and
a resin seal that seals in the semiconductor device and the wires,
wherein said island has through hole formed between a) said first section of said island on which said semiconductor elements mounted and b) said second section of said island on which all said wires are bonded.
7. A semiconductor device according to claim 6, wherein said through hole is formed beneath all of said wires.
8. A semiconductor device comprising:
an island at only one end of only one lead terminal, said island having a first section and a second section,
a semiconductor element whose bottom surface is mounted on said first section of the island,
one or more wires that connect a top surface of the semiconductor element to said second section of the island, and
a resin seal that seals in the semiconductor device and the wires,
wherein said island has a cut formed between said first section on which said semiconductor element is mounted and said second section on which said wires are bonded,
wherein said cut is so formed as to extend below all of said wires.
9. A semiconductor device according to claim 1, wherein all said wires that connect the top surface of the semiconductor element to the island cross over the cut.
10. A semiconductor device according to claim 8, wherein all said wires that connect the top surface of the semiconductor element to the island cross over the cut.
11. A semiconductor device according to claim 6, wherein all said wires that connect the top surface of the semiconductor element to the island cross over the through hole.
US08/750,974 1995-05-11 1996-05-10 Semiconductor device Expired - Fee Related US6242801B1 (en)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
JP11330395 1995-05-11
JP7-113303 1995-05-11
JP10572596A JP3907743B2 (en) 1995-05-11 1996-04-25 Semiconductor device
JP8-105725 1996-04-25
PCT/JP1996/001267 WO1996036074A1 (en) 1995-05-11 1996-05-10 Semiconductor device

Publications (1)

Publication Number Publication Date
US6242801B1 true US6242801B1 (en) 2001-06-05

Family

ID=26445967

Family Applications (1)

Application Number Title Priority Date Filing Date
US08/750,974 Expired - Fee Related US6242801B1 (en) 1995-05-11 1996-05-10 Semiconductor device

Country Status (8)

Country Link
US (1) US6242801B1 (en)
EP (1) EP0771027B1 (en)
JP (1) JP3907743B2 (en)
KR (1) KR100370550B1 (en)
CN (1) CN1134073C (en)
DE (1) DE69635334T2 (en)
TW (1) TW301046B (en)
WO (1) WO1996036074A1 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6344689B1 (en) * 1999-10-07 2002-02-05 Rohm Co., Ltd. Optical semiconductor device for surface mounting
US6525418B2 (en) * 2001-05-30 2003-02-25 Kabushiki Kaisha Moric Semiconductor device
US6894371B2 (en) * 2002-02-27 2005-05-17 Sanyo Electric Co., Ltd. Semiconductor device

Citations (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS52129379A (en) 1976-04-23 1977-10-29 Hitachi Ltd Plastic molded semiconductor device
EP0026788A1 (en) 1979-03-09 1981-04-15 Fujitsu Limited Semiconductor device
JPS6234154A (en) 1985-08-08 1987-02-14 Oji Paper Co Ltd Support for photographic printing paper
JPS6353983A (en) * 1986-08-22 1988-03-08 Matsushita Electric Works Ltd Photocoupler
JPH01123356A (en) 1987-11-09 1989-05-16 Nec Corp Mutual supervision control system
JPH01312858A (en) 1988-06-10 1989-12-18 Nec Corp Resin sealed semiconductor device
JPH02159750A (en) 1988-12-13 1990-06-19 Nec Corp Manufacture of semiconductor device
JPH02191378A (en) * 1988-10-25 1990-07-27 Omron Tateisi Electron Co Photoelectric element, manufacture thereof and drive device therefor
JPH05109959A (en) 1991-10-17 1993-04-30 Nec Corp Manufacture of semiconductor device
JPH05190891A (en) * 1992-01-16 1993-07-30 Sharp Corp Lead frame and manufacture of optical device using same
US5270573A (en) * 1991-02-18 1993-12-14 Mitsubishi Denki Kabushiki Kaisha Resin mold field effect semiconductor device
JPH0661523A (en) * 1992-08-07 1994-03-04 Sharp Corp Reflection type photocoupler and its manufacture
US5313095A (en) * 1992-04-17 1994-05-17 Mitsubishi Denki Kabushiki Kaisha Multiple-chip semiconductor device and a method of manufacturing the same
US5397905A (en) * 1993-02-16 1995-03-14 Fuji Electric Co., Ltd. Power semiconductor device having an insulated gate field effect transistor and a bipolar transistor
US5459350A (en) * 1993-01-13 1995-10-17 Mitsubishi Denki Kabushiki Kaisha Resin sealed type semiconductor device
US5479050A (en) * 1990-10-18 1995-12-26 Texas Instruments Incorporated Leadframe with pedestal
US5491360A (en) * 1994-12-28 1996-02-13 National Semiconductor Corporation Electronic package for isolated circuits
US5563441A (en) * 1992-12-11 1996-10-08 Mitsubishi Denki Kabushiki Kaisha Lead frame assembly including a semiconductor device and a resistance wire
US5598038A (en) * 1993-11-11 1997-01-28 Nec Corporation Resin encapsulated semiconductor device
US5661342A (en) * 1994-11-09 1997-08-26 Mitsubishi Denki Kabushiki Kaisha Semiconductor device with heat sink including positioning pins
US5704593A (en) * 1993-09-20 1998-01-06 Nec Corporation Film carrier tape for semiconductor package and semiconductor device employing the same
US5767573A (en) * 1995-10-26 1998-06-16 Mitsubishi Denki Kabushiki Kaisha Semiconductor device

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS57154863A (en) * 1981-03-19 1982-09-24 Fujitsu Ltd Manufacture of resin sealing type electronic parts
JPH01123356U (en) * 1988-02-16 1989-08-22

Patent Citations (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS52129379A (en) 1976-04-23 1977-10-29 Hitachi Ltd Plastic molded semiconductor device
EP0026788A1 (en) 1979-03-09 1981-04-15 Fujitsu Limited Semiconductor device
US4392152A (en) * 1979-03-09 1983-07-05 Fujitsu Limited Semiconductor device
JPS6234154A (en) 1985-08-08 1987-02-14 Oji Paper Co Ltd Support for photographic printing paper
JPS6353983A (en) * 1986-08-22 1988-03-08 Matsushita Electric Works Ltd Photocoupler
JPH01123356A (en) 1987-11-09 1989-05-16 Nec Corp Mutual supervision control system
JPH01312858A (en) 1988-06-10 1989-12-18 Nec Corp Resin sealed semiconductor device
JPH02191378A (en) * 1988-10-25 1990-07-27 Omron Tateisi Electron Co Photoelectric element, manufacture thereof and drive device therefor
JPH02159750A (en) 1988-12-13 1990-06-19 Nec Corp Manufacture of semiconductor device
US5479050A (en) * 1990-10-18 1995-12-26 Texas Instruments Incorporated Leadframe with pedestal
US5270573A (en) * 1991-02-18 1993-12-14 Mitsubishi Denki Kabushiki Kaisha Resin mold field effect semiconductor device
JPH05109959A (en) 1991-10-17 1993-04-30 Nec Corp Manufacture of semiconductor device
JPH05190891A (en) * 1992-01-16 1993-07-30 Sharp Corp Lead frame and manufacture of optical device using same
US5313095A (en) * 1992-04-17 1994-05-17 Mitsubishi Denki Kabushiki Kaisha Multiple-chip semiconductor device and a method of manufacturing the same
JPH0661523A (en) * 1992-08-07 1994-03-04 Sharp Corp Reflection type photocoupler and its manufacture
US5563441A (en) * 1992-12-11 1996-10-08 Mitsubishi Denki Kabushiki Kaisha Lead frame assembly including a semiconductor device and a resistance wire
US5459350A (en) * 1993-01-13 1995-10-17 Mitsubishi Denki Kabushiki Kaisha Resin sealed type semiconductor device
US5397905A (en) * 1993-02-16 1995-03-14 Fuji Electric Co., Ltd. Power semiconductor device having an insulated gate field effect transistor and a bipolar transistor
US5704593A (en) * 1993-09-20 1998-01-06 Nec Corporation Film carrier tape for semiconductor package and semiconductor device employing the same
US5598038A (en) * 1993-11-11 1997-01-28 Nec Corporation Resin encapsulated semiconductor device
US5661342A (en) * 1994-11-09 1997-08-26 Mitsubishi Denki Kabushiki Kaisha Semiconductor device with heat sink including positioning pins
US5491360A (en) * 1994-12-28 1996-02-13 National Semiconductor Corporation Electronic package for isolated circuits
US5767573A (en) * 1995-10-26 1998-06-16 Mitsubishi Denki Kabushiki Kaisha Semiconductor device

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6344689B1 (en) * 1999-10-07 2002-02-05 Rohm Co., Ltd. Optical semiconductor device for surface mounting
US6525418B2 (en) * 2001-05-30 2003-02-25 Kabushiki Kaisha Moric Semiconductor device
US6894371B2 (en) * 2002-02-27 2005-05-17 Sanyo Electric Co., Ltd. Semiconductor device

Also Published As

Publication number Publication date
EP0771027A4 (en) 2000-01-05
JPH0927577A (en) 1997-01-28
DE69635334D1 (en) 2005-12-01
EP0771027B1 (en) 2005-10-26
EP0771027A1 (en) 1997-05-02
TW301046B (en) 1997-03-21
JP3907743B2 (en) 2007-04-18
CN1154180A (en) 1997-07-09
KR100370550B1 (en) 2003-07-18
DE69635334T2 (en) 2006-07-20
KR970705180A (en) 1997-09-06
WO1996036074A1 (en) 1996-11-14
CN1134073C (en) 2004-01-07

Similar Documents

Publication Publication Date Title
US6177721B1 (en) Chip stack-type semiconductor package and method for fabricating the same
KR970018432A (en) Semiconductor device with lead on chip structure
KR980006163A (en) Resin Sealed Semiconductor Device and Manufacturing Method Thereof
KR970067781A (en) Semiconductor device, manufacturing method thereof, and collective semiconductor device
US5479050A (en) Leadframe with pedestal
JPH088280A (en) Electronic parts and its manufacturing method
US6242801B1 (en) Semiconductor device
US6541856B2 (en) Thermally enhanced high density semiconductor package
JPH0286184A (en) Optoelectronic device
USH73H (en) Integrated circuit packages
KR100438876B1 (en) Chip module
JP3183715B2 (en) Resin-sealed optical element
KR100220244B1 (en) Stack package using solder bump
KR970077602A (en) A padless leadframe having a tie bar integrally formed with a chip bonding portion and a semiconductor chip package
KR100221918B1 (en) Chip scale package
KR950005456B1 (en) Plastic encapsulate semiconductor device
JP3710522B2 (en) Optical semiconductor device and manufacturing method thereof
JP2528023Y2 (en) Optical coupling device
KR100336761B1 (en) Stacked buttom lead package and manufacturing method thereof
KR0124545Y1 (en) Step type package
JPS61276273A (en) Switching element
KR200157437Y1 (en) Semiconductor device using bonding solution
JPS59198744A (en) Resin sealed type semiconductor device
KR100567045B1 (en) A package
KR200154510Y1 (en) Lead on chip package

Legal Events

Date Code Title Description
AS Assignment

Owner name: ROHM CO., LTD., JAPAN

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:SANO, MASASHI;REEL/FRAME:011710/0485

Effective date: 20010206

AS Assignment

Owner name: ROHM CO., LTD., JAPAN

Free format text: CORRECTIVE ASSIGNMENT TO CORRECT THE ASSIGNEE'S ADDRESS, PREVIOUSLY RECORDED AT REEL 011710 FRAME 0485;ASSIGNOR:SANO, MASASHI;REEL/FRAME:012299/0775

Effective date: 20010602

FEPP Fee payment procedure

Free format text: PAYOR NUMBER ASSIGNED (ORIGINAL EVENT CODE: ASPN); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY

FPAY Fee payment

Year of fee payment: 4

FPAY Fee payment

Year of fee payment: 8

REMI Maintenance fee reminder mailed
LAPS Lapse for failure to pay maintenance fees
STCH Information on status: patent discontinuation

Free format text: PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362

FP Lapsed due to failure to pay maintenance fee

Effective date: 20130605